Description

Font Size Picker seems to be broken since v16.9.0 release. See the issue below.

Step-by-step reproduction instructions

1. Add these font sizes to theme.json:

"fontSizes": [
	{
		"size": "0.5rem",
		"slug": "caption",
		"name": "Caption"
	},
	{
		"size": "1rem",
		"slug": "x-small",
		"name": "XS"
	},
	{
		"size": "2rem",
		"slug": "small",
		"name": "S"
	},
	{
		"size": "3rem",
		"slug": "medium",
		"name": "M"
	},
	{
		"size": "4rem",
		"slug": "large",
		"name": "L"
	},
	{
		"size": "5rem",
		"slug": "x-large",
		"name": "XL"
	},
	{
		"size": "6rem",
		"slug": "xx-large",
		"name": "XXL"
	}
]

2. Try selecting a font size with Gutenberg plugin disabled (or with Gutenberg plugin v16.8.1), you will see Font Size Picker displayed correctly:
   

3. Enable Gutenberg 16.9.0, Font Size Picker displays nonsense - order is incorrect, default sizes displays incorrect values (in pixels, however it still works fine on the frontend)
   

Please confirm that you have searched existing issues in the repo.

Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

Yes